Recapping and resistance in Apis mellifera against the parasite Varroa destructor: the queen swap experiment

Webb, G

Abstract

Honey bee colonies worldwide are currently facing an unrelenting threat to their survival from the parasitic mite Varroa destructor. Although, resistance behaviours; such as recapping; appear to be effective by reducing mite infestations. In our first study, named the queen swap experiment, the queens of mite resistant colonies were swapped with the queens of mite non-resistant colonies. We found that resistant queen colonies displayed higher average recapping levels in comparison to non-resistant queen colonies. Though, the ratio of recapped cells to non-infested normal cells (non-recapped cells) were not significantly different between the resistant and non-resistant queen colonies. The total infestation levels were higher in non-resistant queen colonies in contrast to resistant queen colonies, but with no significant difference. A sugar shake test revealed that non-resistant queen colonies had higher infestation levels in comparison to resistant queen colonies, yet the results indicated no significant difference. Likewise, the mite fall test revealed that there was higher infestation levels in non-resistant queen colonies as opposed to resistant queen colonies, again no significant difference was found. In the second study, we established that of the 14 UK apiaries, nine apiaries displayed a higher average recapping levels in comparison to the average infestation levels. Whereas, five apiaries revealed that these colonies had higher average infestation levels respectively. However, no significant difference was found between the average recapping levels and infestation levels of all 14 apiaries. In our third study, we found that the recapped diameter of infested cells was significantly larger in comparison to that of non-infested cells. Finally, we revealed a significant difference between the lower levels of recapping in mite non-reproductive cells in comparison to the higher levels of recapping observed in mite reproductive cells. Due to these results, it must be considered whether there is either an indirect or direct relationship between recapping and infestation levels. Accordingly, recapping could be deemed to be a detection strategy with the purpose of detecting infested cells. If recapping is found to be an important and heritable trait in terms of resistance to Varroa then the measurement of the recapping trait in colonies may predict whether a colony could survive high mite infestations. Subsequently, it is important that the role of recapping should be further explored in this research field.

Citation

Webb, G. Recapping and resistance in Apis mellifera against the parasite Varroa destructor: the queen swap experiment. (Dissertation). University of Salford

• Thesis Type: Dissertation
• Deposit Date: Apr 12, 2023
• Publicly Available Date: Apr 12, 2023
• Award Date: Aug 2, 2022